Answer :
[tex]6z-15>4z+11\\
2z>26\\
z>13\\\\
6z-15<4z+11\\
2z<26\\
z<13
[/tex]
[tex]6z -15 \geq 4z+11 \\\\ 6z-4z \geq 11+15 \\\\ 2z \geq 26 \ |:2 \\\\ z \geq 13 \\\\ \boxed{x=[13;\infty)}[/tex]